The invention relates to an access arm head carrier having a magnetic head for use in a magnetic disk storage consisting of a coaxial stack of flexible magnetic storage disks and in which the access arm can be selectively inserted between two magnetic disks during the rotation of the disks. One of the disks, by means of the access arm, is angularly bent in the form of a circle sector or an approximate circle sector in relation to the normal disk plane. The magnetic disks are guided in a spaced relationship from the surfaces of the magnetic head carrier by air bearings formed by air currents caused by the rotation of the magnetic disks.
It is known (IBM TECHNICAL DISCLOSURE BULLETIN, Volume 12, Number 1, June 1969, Page 81) to design an access mechanism for a magnetic disk storage consisting of a coaxial stack of co-rotating flexible magnetic storage disks in such a manner that two different parts of the access arm during the rotation of the disks can be successively inserted between two magnetic disks at a selected point of the disk pack. The part of the access mechanism which is inserted first causes the magnetic disks below (to a first side) the point of insertion to be angularly bent downwards in the form of a circle sector in relation to the disk plane. This action axially enlarges the space between disks at the point of insertion, so that a separate access arm to which the magnetic head is fixed and which is subsequently inserted can be applied to the bottom (recording) side of the magnetic disk above the point of insertion for recording/sensing data signals.
The known arrangement has the disadvantage that the access mechanism consists of two parts, whose access motions are performed successively. This arrangement leads to considerable delays in the access times, since each transducing access requires two successive mechanical operations.
It is also known (U.S. Pat. No. 3,703,713) to design an access mechanism with a magnetic head for a magnetic disk storage consisting of flexible magnetic disks in such a manner that it comprises a single access arm to which the magnetic head is fixed. The magnetic head carrier of the access arm which can be inserted between the magnetic disks at a selected point of the disk pack serves, on the one hand, to guide the disks at the point of insertion and, on the other, to support the magnetic head on the recording track. A magnetic disk is selected from the pack via a guide gap in the tip of the magnetic head carrier into which a magnetic disk for recording/sensing data is received by the access arm. As a result of the rotation of the magnetic disks, the confining surfaces of this guide gap lead to air bearings, by means of which the magnetic disk is guided at a short distance from the confining surfaces. The magnetic head for recording/sensing data is arranged flush with one of the confining surfaces of the guide gap on the surface plane.
The latter arrangement has the disadvantage that the access arm inserted into the disk pack operates with four surface planes of three magnetic disks. The guide gap of the access arm which, as a function of track addressing, is inserted onto a particular magnetic disk for recording/sensing data leads to substantial air resistances as a result of the radial depth of insertion, thus rendering the position of the access arm within the insertion space of the disk pack unstable.
It is the object of the present invention to design an access arm with a magnetic head for a magnetic disk storage consisting of a coaxial stack (disk pack) of flexible magnetic record disks in such a manner that the magnetic head, adjusted to a recording track on a magnetic disk is retained in a predetermined constant position in relation to the surface of the magnetic disk for recording/sensing data, irrespective of the radial depth of insertion.
This problem is solved in accordance with the present invention in that the surface shape of the magnetic head carrier insertable between two magnetic disks forms at least three areas of different distances between the surfaces of the magnetic head carrier and the magnetic disks defining the transducer access opening.
This arrangement has the advantage that in the transducer access opening of the disk pack, which is formed by only two magnetic disks, stabilizing bearing forces are generated for the magnetic disks passing along the magnetic head carrier of the access arm. These forces are produced by the air flows being subdivided into individual flows, whose magnitude can be chosen as a function of the dimensions of the different distances. The arrangement described has the further advantage that as a result of the irregular surface shape of the confining elements of the magnetic head carrier, air circulation channels are formed by means of which differences in pressure occurring on the leading or trailing edge of the access arm are compensated for.
The foregoing and other objects, features, and advantages of the invention will become apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawing.